Networked PID Controllers for Wireless Systems
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Networked control systems (NCS) have recently been attracting significant attention as they are easier to monitor and modify and have reduced costs for wiring compared to the standard wired solutions. Wireless systems, on top of these traits, can overcome several physical impossibilities of wiring, i.e. they could enable installing a sensor on a rotating mill. However, wireless communication systems have evident imperfections, such as time-varying delay and packet dropout. The stochastic packet transmission process makes the critical assumptions of classical control theory appear invalid. Therefore new system theory and engineering methodology for NCSs need to be developed.
PID Controllers, being simple and effective, overwhelmingly dominate the industrial controllers. It is not far-fetched to believe that, as the migration from wired systems to wireless systems continues, PID controllers will remain the dominant controllers in industry. This study, therefore investigates the application of PID controllers to wireless systems. Two particular control structures from the literature have been examined, followed by a newly developed estimation-based controller structure for networked PID control. Various simulations have been conducted on many types of plants, and the robustness of the system against packet losses and plant uncertainties, among others, have been evaluated. It has been shown that the newly proposed controller structure has a significantly better performance than earlier proposals. The results have been verified by an implementation on a water tank system.
Place, publisher, year, edition, pages
2010. , 61 p.
Electrical Engineering, Electronic Engineering, Information Engineering
IdentifiersURN: urn:nbn:se:kth:diva-105119OAI: oai:DiVA.org:kth-105119DiVA: diva2:570067
Master of Science - Systems, Control and Robotics
Johansson, Mikael, Professor